This application claims priority of Taiwan patent application no. 090215437, filed on Sep. 7, 2001.
1. Field of the Invention
The invention relates to a safety switch for a vehicle starting system, more particularly to a safety switch for ensuring that remote-controlled activation of a vehicle is possible only when an engine hood is in a closed state.
2. Description of the Related Art
When starting a vehicle, the driver of the vehicle will, through the action of a starting system, activate an ignition system for driving operation of an engine system and a linkage system of the vehicle. Aside from using a key to start a vehicle, it is also known heretofore to use a remote controller for remote-controlled activation of the vehicle.
However, untimely activation of the remote controller while the vehicle is being repaired will expose a mechanic to danger. With reference to FIG. 1, because an engine hood of the vehicle is normally in an opened state when repairing the latter, a safety switch 2 can be coupled to a control line 11 of the starting system 1 such that remote-controlled activation of the vehicle is enabled only when the opened state of the engine hood is detected by the safety switch 2. As shown in FIG. 1, one end portion 111 of the control line 11 is connected to the starting system 1. The other end 112 of the control line 11 is formed with first and second branches 12, 13. The first branch 12 is connected to a +5V voltage source. The second branch 13 is terminated by a first electrical connector 14. The safety switch 2 has a first end 21 terminated by a second electrical connector 22 that complements the first electrical connector 14. As such, electrical connection between the starting system 1 and the safety switch 2 is established when the first and second electrical connectors 14, 22 are inter-engaged. The safety switch 2 further has a grounded second end 23. The safety switch 2 conducts, i.e. electrical connection between the first and second ends 21, 23 is made, such that a ground voltage is provided to the control line 11 via the safety switch 2 when the engine hood is in an opened state. The safety switch 2 is cut-off, i.e. electrical connection between the first and second ends 21, 23 is broken, such that the +5 voltage is provided to the control line 11 when the engine hood is in a closed state. As such, when the starting system 1 receives a remote control signal for remote-controlled activation of the vehicle from a remote controller (not shown), the starting system 11 will first detect the voltage signal present at the control line 11. If the +5 voltage is present at the control line 11, the starting system 1 will be enabled to permit remote-controlled starting of the engine system of the vehicle. Otherwise, if the ground voltage is present at the control line 11, the starting system 1 will be inhibited from permitting the remote-controlled starting of the engine system of the vehicle. Therefore, activation of the vehicle by remote control can be avoided when the engine hood is in the opened state so as to result in a safer environment for mechanics.
However, it is noted that the connection between the first and second electrical connectors 14, 22 is likely to loosen over a period of time. When the first and second electrical connectors 14, 22 are improperly connected, the safety switch 2 will be unable to provide the ground voltage to the control line 11 in the event that the engine hood of the vehicle is in the opened state. Under such a condition, the +5 voltage will always be present at the control line 11, thereby resulting in the possibility of undesired starting of the engine system by remote control.
In addition, when the safety switch 2 breaks down and is always cut-off, no indication is provided as to the need to replace the safety switch 2.
Therefore, the main object of the present invention is to provide a safety switch for ensuring that remote-controlled activation of a vehicle starting system is possible only when an engine hood is in a closed state.
Another object of the present invention is to provide a safety switch that can indicate the need to replace a broken switch element thereof.
According to the present invention, a safety switch is adapted to be coupled to a control line of a starting system of a vehicle. The starting system is operable so as to detect a voltage signal present at the control line upon receipt of a remote control signal for remote-controlled activation of the vehicle from a remote controller. The voltage signal indicates position state of an engine hood of the vehicle. The safety switch is adapted to inhibit the starting system so as to prevent the remote-controlled activation of the vehicle when the position state of the engine hood corresponds to an opened state, and is adapted to enable the starting system so as to permit the remote-controlled activation of the vehicle when the position state of the engine hood corresponds to a closed state. The control line has an end portion formed with first and second branches. The safety switch comprises:
a first electrical connector adapted to terminate the second branch of the control line;
a first resistor adapted to connect the first branch of the control line to a first voltage source that has a first voltage output;
a switch element having a first end adapted to be connected to a second voltage source that has a second voltage output lower than the first voltage output, and an opposite second end, the switch element being adapted to detect the position state of the engine hood, and making electrical connection between the first and second ends when the position state of the engine hood corresponds to the opened state, and breaking the electrical connection between the first and second ends when the position state of the engine hood corresponds to the closed state;
a second electrical connector for terminating the second end of the switch element, the second electrical connector complementing the first electrical connector so as to be adapted to connect the switch element to the second branch when the second electrical connector engages the first electrical connector; and
a second resistor connected in parallel with the switch element between the first and second ends.
When the first and second electrical connectors are properly connected, and the position state of the engine hood corresponds to the opened state, the voltage signal at the control line corresponds to the second voltage output in view of the connection between the second branch and the second voltage source via the first and second electrical connectors and the switch element, thereby inhibiting the starting system so as to prevent the remote-controlled activation of the vehicle.
When the first and second electrical connectors are properly connected, and the position state of the engine hood corresponds to the closed state, the voltage signal at the control line corresponds to a voltage drop that is less than the first voltage output and greater than the second voltage output in view of the connection between the second branch and the second voltage source via the first and second electrical connectors and the second resistor, thereby enabling the starting system so as to permit the remote-controlled activation of the vehicle.
When the first and second electrical connectors are improperly connected such that the switch element is disconnected from the second branch, the voltage signal at the control line corresponds to the first voltage output, thereby inhibiting the starting system so as to prevent the remote-controlled activation of the vehicle.
Preferably, a light emitting diode is connected in series with the second resistor between the first and second ends of the switch element, and can indicate whether or not the switch element is broken and needs to be replaced.